Improvements show how to get more efficiency from natural gas

Nation's Restaurant News, April 3, 1989 by Patt Patterson

Improvements show how to get more efficiency from natural gas

You may not have noticed it, but commercial gas cooking equipment is getting more efficient all the time. Over the past decade or more, the main driving force behind those improvements has been the Gas Research Institute, located in Chicago.

"We're working on a number of different approaches to improve the performance of gas equipment," according to GRI's Donald Fritzshe, senior project manager for commercial appliances. "In addition to in-house research and development here, we fund projects with the American Gas Association Laboratories and with Battelle-Columbus Laboratories through our Gas Appliance Technology Center."

The Gas Research Institute was organized and is regulated by the Federal Energy Regulatory Commission. The institute is a private, not-for-profit membership organization that plans, manages, and develops financing for cooperative research and development programs in gaseous fuels and their use.

"We've just developed a double-sided gas-fired griddle that can cook food like hamburgers and steaks in less than half the time an ordinary griddle takes," Fritzshe said. "The concept that makes this possible is heat transfer fluids. The heat is supplied to the griddle surface by conduction from a super-heated fluid.

"Although the food never comes in contact with the fluid, it is non-toxic and safe for kitchen use.

One of the research and development projects conducted in cooperation with equipment manufacturers is a pulsed combustion technology, which may be used for griddles and deep fat fryers.

"Controlled amounts of air and natural gas are injected in a combustion chamber," Fritzshe explained. "To start the combustion, a spark plug is used, just as in an automobile engine. Then a valve opens, drawing in another charge of air and gas with the negative pressure created by the first combustion. Heat within the chamber then detonates the charge, and the cycle continues.

"This produces extremely high efficiencies of up to 80 percent. That can be compared with ordinary burner efficiencies of 40 percent to 50 percent and efficiencies of 65 percent to 70 percent for current high efficiency burners."

Fritzshe said he believes that within the next couple of years GRI will have completed development on a gas-fired combination steamer and convection oven that will take a full-sized 18-inch-by-26-inch baking pan and operate at efficiencies as much as twice as great as today's steamer-ovens.

"It's based on a unique heat exchanger approach," Fritzshe pointed out. "We're working on the patents for it now." Another project is development of a gas-fired "rethermalization" oven.

According to Fritzshe, all earlier cook and chill appliances have been electrical. The concept involves cooking food and then chilling it and holding it at 35 degrees F. to 36 degrees F.

The food is cooked in a large pan, where it stays during refrigerated storage up to several days. It is then reheated to serving temperature, all in the same piece of equipment.

"Another project that recently reached the market is the range-top power burner," Fritzshe said. "This project was the result of three years of joint effort by GRI, the AGA Laboratories, the Battelle-Columbus Laboratories, and a major appliance manufacturer. The new burner has an energy efficiency of about 60 percent, compared with about 40 percent for conventional burners.

"The power burner premixes air and gas in the right proportions for maximum combustion efficiency. The mixture is then forced into the burner head, which is enclosed in a metal ring. Not only does the design produce heat more efficiently, but it also cooks faster.

Compared with a conventional burner, the power burner works almost 36 percent faster, while using 34 percent less energy."

Gas cooking appliances aren't the only area of research and development going on at GRI. Another project group is working on a flexible plastic-coated corrugated-steel pipe that will make it possible to plumb a building for natural gas almost as easily as it can now be wired for electricity.

Sources say the device could permit cooking equipment to just plug into a wall or floor outlet like electrical equipment.

Another ongoing project outside Fritzshe's realm is aimed at permitting even medium-sized restaurants and institutions to generate their own electricity with natural gas. Surplus electricity could then be sold to the local utility to lower the costs of generating it. It's called co-generation.

When Fritzshe was asked about future appliance projects at GRI, he said he had to think a minute, because there were so many.

"We're working on an integrated kitchen concept," he responded. "Using a remote combustion unit, we're investigating the use of heat transfer fluids to provide the cooking temperatures in a wide range of equipment ranging from ovens to deep-fat fryers to griddles. The advantages of using HTF is that you can put the heat where you need it and get it into places where it's difficult to put a glass flame."